Nuclear power plant

ABSTRACT

Nuclear power plant with a reactor building, a fuel building, buildings for the ancillary nuclear, electrical and safety equipment, and a building for turbo-electric machines. The group of buildings is in the general shape of a T, with the fuel and ancillary equipment buildings (2) and (3) in line at both sides of the reactor building, and the engine building (6) facing the reactor building (1) and perpendicular to the latter. The vault of the protective enclosure is connected to the foundation of the reactor building and is in the shape of a cylinder with horizontal generatrices. The invention is applicable to light water nuclear power stations.

BACKGROUND OF THE INVENTION

The present invention concerns a new nuclear power plant, moreparticularly for a light water power station. It also concerns a methodof constructing such a power station.

The plant as a whole for a nuclear power station has to date beenorganized around a central building termed the "reactor building"containing the core of the reactor and the primary cooling circuitloops, and in particular the steam generators. In known plants, thereactor building is in the form of a very tall concrete structure, inthe shape of a circular cylinder with vertical axis. The buildingcontaining the electric turbogenerator or engine room, the building forthe fuel as well as the various ancillary buildings are then distributedall around the reactor building.

This conventional arrangement, which as far as use of the power stationis concerned, is generally satisfactory, does, however, present thedisadvantage of causing considerable delays in construction. Inpractice, the construction of a conventional power station of the lightwater type and in particular the complete erection of the reactorbuilding at present involves two stages.

The first stage is that of constructing the building, properlyso-called, or the civil engineering phase of execution. It involvesconstructing a concrete foundation on which the various concreteelements are mounted, such as the biological shields, the protectivechambers for the steam generators, etc. At the upper part of the vessel,a revolving bridge is then mounted which will be used first for puttingheavy equipment in position and then, during use, for various handlingoperations.

The second stage is that of putting heavy equipment in position, whichcan only be done after completion of the first stage. In practice thecleanness required for the pieces of equipment constituting thecirculation loops of the primary fluid between the reactor-core and thesteam generators make it impossible to carry out heavy civil engineeringwork in their vicinity. Furthermore, it is at present necessary for therevolving bridge to be in position at the upper part of the enclosure sothat the heavy units, such as the reactor vessel, the pressurizer or thesteam generators can be put in position. An additional fact is thataccess to the site of the reactor building is made difficult by thepresence all around the construction sites of attached buildings. Itwill also be noted that maneuvering at the bridge of the steamgenerators, which have been brought into the building at the level ofthe working floor, necessitates setting them upright again and thenraising them by a height which is sufficient to bring them to thevertical on their supports in the protective chambers before they areleft in position there. This makes it necessary to have considerableheight under the bridge and consequently for the reactor building tohave a considerable height, which increases its cost and its sensitivityto earthquakes and makes it essential to increase its strength.

SUMMARY OF THE INVENTION

The present invention leads to a general overall architecture for thevarious buildings of a nuclear power station which is such that thevarious construction operations can easily overlap, allowing the site tobe better organized and time and construction costs to be reduced.

The invention is applicable to a nuclear power plant, the variousprincipal buildings constructed on a foundation consisting of:

a reactor building with the reactor core and a primary cooling circuitbetween the core and at least one steam generator,

a fuel building for the handling of new and used fuel,

buildings for the ancillary nuclear, electrical and safety equipment,and

an engine building for the turbogenerator units.

According to the invention, the group of buildings is arranged in thegeneral shape of a T, with the fuel and ancillary buildings arranged inline and adjacent either side of the reactor building, the enginebuilding being disposed facing and perpendicular to the reactorbuilding; in the case of the reactor building, at least, the vault ofthe protective enclosure is connected to the foundation and is in theform of a cylinder with horizontal generatrices parallel to thelongitudinal axis of the reactor building and the ancillary buildings.

According to a preferred embodiment of the invention, at least in thecase of the reactor building, the vault of the protective enclosure andthe foundation are united rigidly so as to constitute a monolithictubular assembly, the thick lower part of which is constituted by thefoundation, and so as to allow the vault to be pre-stressed on thefoundation.

The invention is also applicable to the method of constructing such apower station. According to the invention, concurrently with theconstruction and equipping of the engine building, procedure isaccording to the following successive phases:

(a) construction of the supporting foundation for the reactor buildingand the ancillary buildings,

(b) establishing of service tracks parallel with and on both sides ofthe frame, with positioning of lifting and transporting means on theseservice tracks,

(c) construction of concrete inner structures of the reactor buildingand the attached buildings, with units prefabricated on an auxiliarysite and brought and put in position by the lifting and transportingmeans,

(d) simultaneously, as their supports are constructed and using the samemeans of lifting and transporting, positioning of large pieces ofequipment in their respective buildings,

(e) putting in position of the vault of the protective enclosure of thereactor building, made of units prefabricated on an auxiliary site,brought to their locations by the lifting and transporting means runningon the service tracks and then assembled together to form a continuousvault.

The invention will be better understood by referring to a particularembodiment given by way of example and represented by the attacheddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall plan in perspective on a very small scale showing,in accordance with the invention, the new relative arrangement of thevarious buildings constituting the nuclear power station.

FIGS. 2 and 3 show in more detail the inner arrangement of thebuildings. FIG. 2 is a plan view of the reactor building and theancillary nuclear and safety equipment buildings; FIG. 3 is an elevationin transverse section of the reactor building.

FIGS. 4 to 7 illustrate the new method of constructing such a powerstation. FIG. 4 is an overall plan of the site; FIGS. 5, 6 and 7 showthree characteristic stages of the construction of the reactor building.

DETAILED DESCRIPTION OF AN EMBODIMENT

Firstly, in FIG. 1, the general organization of the power station isshown in the shape of a T, with the reactor building 1 in the center,extended on both sides and in the same line by the building 2 for theancillary nuclear equipment and the building 3 for the ancillaryelectrical and safety equipment. The reactor building here includes fourcooling loops and four protective chambers 5 for outlet of the steampipes to the engine room 6.

FIGS. 2 and 3 show the inner arrangement of the buildings, and moreparticularly of the reactor building, in more detail. Thus, in thereactor building 1, there is the vessel 7 for the reactor core, with atravelling crane 8 for handling pieces of equipment inside and theswimming pool 9 for the reactor. Each primary water circulation loopbetween the core 7 and a steam generator 10, with a circulating pump, isrepresented here very diagrammatically by a unit 11, from which a steampipe 12 issues. A principal isolating valve in a protective chamber 5,after passing through the protective enclosure 15, is more easilyvisible in FIG. 3. The series of safety valves will be disposed at 16above the protective chamber.

In the adjacent attached building 2, the fuel building 18 occurs firstwith the racks 19 for storing fuel assemblies and the lock 20 forcommunication with the reactor swimming pool.

The region 21 of the building 2 constitutes a first building forancillary nuclear equipment, with the make-up water and the circuit formonitoring the primary circuit volumetrically and chemically. The region22, also for ancillary nuclear equipment, includes demineralizationfilters and the circuit for treating effluents.

On the other side of the reactor building, the building 3 has ancillaryelectrical equipment 24 and ancillary safety equipment 25.

A short description of the development of the construction of the powerstation, illustrated by FIGS. 4 to 7, will now show how the arrangementjust described allows a reduction in the length of time required overallto construct the power station.

After the excavation work, construction of the foundation 28 with thereactor vessel pit 29 and piers 30 and then filling in, if necessary,can take place. A single foundation is preferably made for the reactorbuilding and the ancillary building around it, so that a monolithicassembly is obtained which will resist earthquakes. Alongside, servicetracks 33, for allowing cranes or any other lifting and transportingmeans to run, and which are parallel and on both sides of thefoundation, are then constructed. The tracks 33 extend to twoprefabrication sites 34, at each end of the site as a whole.

A last stage, better illustrated by FIG. 6, exhibits the positioning andassembling of the inner structures of the reactor building, such as, forexample, the reactor vessel pit and the protective chambers for thesteam generator. The units of these structures are prefabricated on oneof the sites 34 and then put in position by means of light cranes 36running on the tracks 33, and by a high-capacity crane 38. Assembly ofthe units can then be carried out by any conventional means. Any type oflifting means adapted to the units to be installed will, of course, beused, and the cranes represented in a simplified way in the drawingcould, if necessary, be replaced by portal cranes straddling the wholewidth of the foundation.

It will be noted that the site is cleaned very rapidly, the presence onthe site of machines for producing concrete not being necessary for thesingle operations of connecting the prefabricated units. In theseconditions, heavy pieces of equipment can be brought in very rapidly, asfast as their supports can be keyed, and without waiting for civilengineering works to be entirely finished. Thus, in FIG. 6, putting thevessel 7 in position by means of the crane 38 is represented. The sameapplies for putting the steam generators, the pressurizer and the pumpsin position.

The complete accessiblity of the entire site, each building beingaccessible from both sides at the same time and over its whole length,will again be noted. This accessibility, combined with the technique ofprefabrication, allows construction to progress simultaneously withputting pieces of equipment in position.

When all the inner structures are finished and the equipment is inplace, all that remains to be done is to cover the whole structure withthe vault of the protective enclosure. The vault can be made ofprefabricated units, each consisting of self-supporting sections. Eachunit to be juxtaposed to form the enclosure can be prefabricated on oneof the sites 34 and then brought on site up to the reactor building bysimple translation along the tracks 33. Such an element 41 carried bycarriages 42 can be seen in more detail in FIG. 7. Once in correctlongitudinal position, the unit can be taken up by jacks so that thecarriages can be disengaged, and then lowered into its final position,represented in chain-dotted lines.

After positioning, the vault is rigidly united with the foundation so asto obtain a tubular assembly whose thick lower part is constituted bythe foundation, and which facilitates the prestressing of the continuousvault.

Positioning of the superstructures of the ancillary buildings can becarried out in the same way, operations for the reactor building, as forthe ancillary buildings, being able to be carried out at both ends atonce. A continuous tubular construction is thus obtained.

Lastly, it will be noted that the embodiment of the power station asjust described not only allows time to be saved in work on the site butalso lessens the height below the vault of the power station, since thisheight no longer depends on the space which is necessary for re-erectingthe steam generators; the power station is then more stable inearthquakes.

The invention is not, of course, strictly limited to the embodimentwhich has just been described by way of example; it also coversembodiments which differ only in detail, variants of execution or theuse of equivalent means. Thus, it is not strictly essential for thetransverse section of the ancillary buildings to be exactly the same asthat of the reactor building they surround. Each ancillary buildingcould also conceivably be constructed on an independent foundation, thefoundations being then connected in a conventional manner. Mostimportantly, they must be aligned with the reactor building, so as toform a site which is easily accessible overall via parallel servicetracks, even if the covering of the ancillary buildings has less height.However, it can be noted that having identical vaults for the reactorbuilding and the ancillary buildings will facilitate prefabrication oftheir units, simplify the operations involved in putting them inposition, and allow continuous tubular construction on a singlefoundation.

Similarly, any method of constructing the vault of the protectiveenclosure of the reactor building other than the forming ofself-supporting units is conceivable, provided these other methods,which can be conventional, allow prefabrication and easy assembly onsite.

It can also be observed that, if the site requires, the prefabricationsites can be further away, additional handling then having to beprovided to bring the prefabricated units to the site of the powerstation and take them up by the service cranes 36 or 38 of the site.

I claim:
 1. Nuclear power plant constructed on a foundation (28),comprising(a) a reactor building (1) containing a reactor core and aprimary cooling circuit between said core and at least one steamgenerator; (b) a fuel building (2) for processing new and used fuel; (c)ancillary buildings (3) for nuclear, electrical and safety equipment;and (d) an engine building (6) for turbogenerator units; (e) saidbuildings (1, 2, 3, 6) being arranged in the general shape of a T, saidfuel building (2) and ancillary building (3) being arranged in line andadjacent either side of said reactor building (1) and perpendicular tothe latter; (f) a protective enclosure for at least said reactorbuilding (1), said enclosure having a vault rigidly united with saidfoundation (28) so as to constitute a monolithic tubular assembly thethick lower part of which constitutes said foundation, and so as topermit prestressing of said vault on said foundation, said vault havingthe shape of a cylinder with horizontal generatrices parallel to thelongitudinal axis of said reactor building (1) and said ancillarybuildings (3).
 2. Nuclear power plant according to claim 1, comprisingvaults of said fuel building (2) and said ancillary having the sameprofile as that of said vault of said reactor building.
 3. Nuclear powerplant according to claims 1 or 2, wherein said reactor building (1) andsaid fuel and ancillary buildings (2, 3) are constructed on a singleone-piece foundation (28), and all the vaults with the same profile areunited with each other and with said single foundation so as toconstitute a monolithic tubular assembly.